U.S. patent number 5,334,258 [Application Number 07/913,047] was granted by the patent office on 1994-08-02 for washing method.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Akira Horie, Akihito Hosaka, Yukihiro Imai, Ikuo Nakajima, Toshiji Nishiguchi, Nagato Osano.
United States Patent |
5,334,258 |
Osano , et al. |
August 2, 1994 |
**Please see images for:
( Certificate of Correction ) ** |
Washing method
Abstract
Disclosed is a washing method in which parts and products are
washed free of residual smudges without using fleon-family
solvents. The method of washing members such as parts or products
comprises a first degreasing step for degreasing in nonaqueous
liquid the members to be washed after worked, a second degreasing
step for degreasing the members being washed in an aqueous liquid
which dissolves the nonaqueous liquid, a finish washing step for
washing in the aqueous liquid, a rinsing step, and a drying step,
wherein the drying step is performed in a plurality of pure water
baths, the temperature of a last pure water bath is established to
a range of 70.degree. to 85.degree. C., and the washed members are
taken out from the pure water bath for drying the surfaces thereof.
Also, the washing method is disclosed in which pure water in a
plurality of the pure water baths has temperature gradient in the
sequence of washing steps. Furthermore, the washing method is
disclosed in which the speed of taking out the washed members from
the last pure water bath is established so as to be in inverse
proportion to the surface area of the washed member.
Inventors: |
Osano; Nagato (Kawasaki,
JP), Imai; Yukihiro (Utsunomiya, JP),
Hosaka; Akihito (Ayase, JP), Nakajima; Ikuo
(Tokyo, JP), Nishiguchi; Toshiji (Kawasaki,
JP), Horie; Akira (Toride, JP) |
Assignee: |
Canon Kabushiki Kaisha
(JP)
|
Family
ID: |
26496760 |
Appl.
No.: |
07/913,047 |
Filed: |
July 14, 1992 |
Foreign Application Priority Data
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Jul 16, 1991 [JP] |
|
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3-175513 |
Sep 18, 1991 [JP] |
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3-237936 |
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Current U.S.
Class: |
134/42; 134/26;
134/40 |
Current CPC
Class: |
B08B
3/04 (20130101) |
Current International
Class: |
B08B
3/04 (20060101); B08B 003/08 () |
Field of
Search: |
;134/26,40,42 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0310922 |
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Apr 1989 |
|
EP |
|
523299 |
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Apr 1931 |
|
DE2 |
|
2852588 |
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Jun 1979 |
|
DE |
|
0028684 |
|
Mar 1981 |
|
JP |
|
403031489 |
|
Feb 1991 |
|
JP |
|
Other References
V Frank, "Chemical Cleaning Technique for Vibratory Bowl Feeder,"
IBM Technical Disclosure Bulletin, vol. 25, No. 11B, Apr. 1983, pp.
6267-6268. .
Patent Abstracts of Japan, vol. 13, No. 557 (P-974) (Dec. 12, 1989)
& JP-A-01 233 413..
|
Primary Examiner: Springer; David B.
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Claims
What is claimed is:
1. A method for washing an article having optical function, said
method comprising the steps of:
degreasing said article, in a degreasing bath containing an organic
solvent;
washing said article in a washing bath containing a surface-active
agent;
washing said article with a washing liquid being heated to about
70.degree. to 80.degree. C.,
removing said article from the washing liquid at a speed of 3 to 8
mm/sec. after a specified time in the washing liquid; and
drying said article.
2. A method according to claim 1, wherein said article is an
optical element of glass, and said taking-out speed is specified
for 20 to 5,000 mm.sup.2 of a surface area of said article.
3. A method according to claim 1, wherein the water in said washing
liquid has a resistivity of more than 10 M.OMEGA..cm.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a washing method for parts or
products, particularly, a washing method for optical parts.
2. Related Background Art
According to conventional practice, machine parts and optical parts
are washed after processed, for example, through steps as shown in
FIG. 7.
The steps of washing will hereinafter be described.
Step a
Pitch adhering to the surface of a member to be washed (not shown)
is removed by a nonaqueous solvent.
The member to be washed is dipped into and taken out from a first
degreasing liquid 201 to a fourth degreasing liquid 204 by a
conveying mechanism (not shown). The four liquids are
perchloroethylene, respectively. Each liquid is at a room
temperature.
Step b
An aqueous liquid (water system) is substituted for said nonaqueous
liquid covering the surface of said member being washed. In other
words, said member being washed is dipped into and taken out from a
first substituting liquid 205 and a second substituting liquid
206.
The first substituting liquid 205 and the second substituting
liquid 206 are aqueous solution containing a surface-active agent.
Each liquid is at a room temperature.
Step c
Finish washing is performed.
Said member being washed is dipped into and taken out from a first
finish washing liquid to a third finish washing liquid.
The first finish washing liquid 207 is city water (tap water). The
second finish washing liquid 208 is an anionic or nonionic
surface-active agent. The third finish washing liquid 209 is
identical to the washing liquid 208.
Step d
Rinsing is performed.
Said member being washed is dipped into and taken out from a first
rinse liquid 210 and a second rinse liquid 211.
Both the first and second rinse liquids are city water.
Step e
Said member being washed is dipped into and taken out from a first
substituting liquid 212 and a second substituting liquid 213 for
substitution of a nonaqueous solvent (nonaqueous system).
Both the first and second substituting liquids are IPA ( isopropyl
alcohol).
Step f
Said IPA adhering to said member being washed is removed by
drying.
The member being washed is held for a predetermined period of time
in freon vapor 214 which is generated by heating freon liquid by a
heater (not shown), and then is taken out therefrom.
In the method of the prior art described above, freon family
solvents are essential. With an increasing demand for environmental
protection in recent years, washing without using freon has been
required, as in various other fields. A major problem in washing
without using freon is, for example, so-called residual smudge
which arises in a drying step after wet washing.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for
washing parts or products free of residual smudges without using
freon solvents.
A washing method according to the present invention for washing
members such as parts or products, comprises a first degreasing
step for degreasing in nonaqueous liquid said members to be washed
after being degreased, a second degreasing step for degreasing said
members being washed in an aqueous liquid dissolving said
nonaqueous liquid , a finish washing step for washing in said
aqueous liquid, a rinsing step, and a drying step, and is
characterized in that said drying step is performed in a plurality
of pure water baths, the temperature of a last pure water bath is
established to be in a range of 70.degree. to 85.degree. C., and
said washed members are taken out from said pure water bath for
drying the surfaces thereof.
Also, said washing method is characterized in that pure water in
said plurality of pure water baths has temperature gradient in the
sequence of washing steps.
Furthermore, said washing method is characterized in that the speed
of taking out said washed members from said last pure water bath is
established so as to be in inverse proportion to the surface area
of said washed member.
When washing works in washing liquid, the action of the washing
liquid's surface tension causes the washing liquid to stay in the
portion between said product or product component and a projection
and between said work and a jig surface, resulting in defective
washing defect, a reduction of rinsing effect, and a deterioration
of drying performance.
A second object of the present invention is to provide a washing
device and a washing method allowing steps of washing, rinsing, and
drying, without any washing liquid remaining as one continuous
process.
A washing device of the present invention has a portable body for
use in washing a member having a hole, and is characterized by
comprising holding means provided on said body for holding said
member to be washed, and a projection provided on said body to be
inserted in noncontact manner into the hole in said member to be
washed.
The washing device can comprise a plurality of sets of holding
means and a projection.
A washing device of the present invention has a portable body for
use in washing a polygonal reflecting mirror having a hole portion
in a bottom surface thereof and side surfaces of mirror, and is
characterized by comprising holding means provided on said body for
holding the bottom surface of said member to be washed in point
contact manner at edge portions thereof, and a projection provided
on said body to be inserted in noncontact manner into the hole
portion in said member to be washed.
The washing device can also comprises a plurality of sets of
holding means and a projection.
Furthermore, the washing method of the present invention for wetly
washing a member of a polygonal reflecting mirror having a hole
portion in a bottom surface thereof and side surfaces of mirror, is
characterized in that after holding the bottom surface of said
member to be washed at edge portions thereof by the holding means
of the washing device of the present invention, and inserting the
projection of said washing jig in noncontact manner into the hole
portion in said member to be washed, said member is washed in
hydrophilic liquid, thereafter the mirror surfaces of said member
being washed are washed in ultra-pure water, and said member washed
in the ultra-pure water is dried together with said washing
device.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an explanatory drawing schematically showing an washing
method according to the present invention.
FIG. 2 is a plan view showing an embodiment of a washing device
(washing jig).
FIG. 3 is a front view of the washing jig shown in FIG. 1.
FIG. 4 is a side view of the washing jig shown in FIG. 1.
FIG. 5 is an explanatory drawing showing the relationship between
the washing jig of the present embodiment and a work.
FIG. 6 is an explanatory drawing schematically showing washing
equipment to be used in the present embodiment.
FIG. 7 is an explanatory drawing schematically showing an washing
method according to an example of the prior art.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will hereinafter be described
with reference to the drawings.
FIG. 1 is an explanatory drawing schematically showing an
embodiment of washing equipment of the present invention.
The present embodiment comprises four degreasing baths 1, 2, 3, and
4, four washing members in nonaqueous liquid, two washing baths 5
and 6 for washing out the nonaqueous liquid, a rinsing bath 7 for
washing members in city water, washing baths 8 and 9 to finish
washing members, rinsing baths 10 and 11 for washing members in
pure water, hot pure water baths 12 and 13 for dipping members into
heated ultra-pure water, and a drying chamber for drying washed
members, i.e. a hot air zone 14.
Next, a washing method according to the present embodiment will be
described.
First, members to be washed (for example, optical glass finished by
a known polishing process) are dipped into the degreasing baths 1,
2, 3, and 4 filled with an organic solvent such as
perchloroethylene for removing adhering pitch, oil and the like
from the members being washed.
The members being washed which have been subjected to the step a
are dipped into the washing baths 5 and 6 filled with a
surface-active agent to finish the step b.
The members being washed which have been subjected to the steps a
and b are dipped into the washing bath 7 filled with city water,
and furthermore are dipped into the washing baths 8 and 9 filled
with a surface-active agent to finish the finish washing step, i.e.
the step c. Then, the members being washed are dipped into the
rinsing baths 9 and 10 filled with pure water to finish the rinsing
step.
The members being washed which have been subjected to the steps a
to d are moved to the step e, i.e. a dipping into hot pure water
step. The members being washed are dipped into the ultra-pure bath
12 filled with ultra-pure water (resistivity is about 10
M.OMEGA..cm or more) which has been purified by ultra-pure water
producing apparatus, described later, and is heated to about
40.degree. C. by a heater (not shown) to finish the dipping into
hot pure water step. Then, the members being washed are moved to a
taking out step, i.e. the step f. The taking out bath 13 is filled
with ultra-pure water having equivalent water quality to the
ultra-pure water contained in the ultra-pure water tank 12, except
in being heated to about 70.degree. C. to 85.degree. C. by a heater
(not shown). The washed members are taken out from the taking out
bath at a taking out speed of 3 to 10 mm/sec. The washed members
taken out are moved to the drying step g for drying by hot air
heated to about 60.degree. C. by a heater (not shown) and cleaned
by a HEPA filter (dust collecting filter) (not shown). This step of
drying by hot air shortens drying time, but may be deleted.
The relationship between a speed of taking out from the taking out
bath 13 and the surface area of a washed member has been obtained
as shown in Table 1.
Cleanliness has been measured for glass lenses which have been
subjected to the above steps for washing, as shown in Table 1.
Lens materials used are BK7, SF6, and LakS, and measurement has
been made visually by lamplight after a polishing process.
TABLE 1 ______________________________________ surface area
taking-out speed (mm.sup.2) (mm/sec)
______________________________________ 3 4 5 6 7 8 20 .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. 50 .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. 100 .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. x 500
.smallcircle. .smallcircle. .smallcircle. .smallcircle. x x 1000
.smallcircle. .smallcircle. .smallcircle. x x x 3000 .smallcircle.
.smallcircle. x x x x 5000 .smallcircle. .smallcircle. x x x x
______________________________________ .smallcircle.: good
cleanliness x: occurrence of washing smudge
COMPARATIVE EXAMPLE
In a comparative example 1 identical with the embodiment except
that ultra-pure water in the ultra-pure water bath 12 is at a room
temperature, washing smudges have occurred in washed members in all
cases.
COMPARATIVE EXAMPLE 2
In a comparative example 2 identical with the embodiment except
that the ultra-pure water bath 12 and the taking out bath 13 are
filled with ordinary water in place of ultra-pure water, washing
smudges have occurred in washed members in all cases.
As described above, according to the present embodiment, a
plurality of pure water baths are provided in a drying step for
parts or products, the temperature of a last pure water bath is set
to a range of 70.degree. to 85.degree. C., and said washed members
are taken out from said pure water bath for drying the surfaces
thereof, thereby implementing washing without residual smudges.
Next, an embodiment of a washing device of the present invention's
second object will be described with reference to the drawings.
FIG. 2 is a plan view showing an embodiment of a washing device of
the present invention. FIG. 3 is a front view of the washing device
shown in FIG. 2. FIG. 4 is a side view of the washing device shown
in FIG. 2. FIG. 5 is an explanatory drawing showing the
relationship between the washing device of the present invention
and a work.
A pallet 21 representative of the washing device (jig) of the
present embodiment is provided with a plurality of arms 23, a
plurality of holding pins 24, and a plurality of insert pins 25, on
a jig base plate 22 as a body having a plurality of openings 21A
and 21B.
A plurality of openings 21A and 21B are provided so as to permit
ultrasonic waves to pass therethrough when the pallet 21 is put in
an ultrasonic washing bath (not shown), and the number, size, shape
and the like thereof are determined according to conditions of the
device to be used and the like. The arms 23 are hooked to be lifted
by conveying equipment (not shown) when the pallet 21 is conveyed.
The holding pins 24 are representative of holding means for holding
the bottom surface of a work 26 in point contact manner at edge
portions thereof, thereby preventing the work 26 from moving during
ultrasonic washing. As shown in FIG. 3, four holding pins per one
work 26 are provided in positions corresponding to bottom surface
edge portions of the work 26. The insert pin 25 is a projection to
inserted in noncontact manner into a hole portion in the work 26
for liquid drainage, described later, and as shown in FIGS. 1 to 3,
the insert pin 25 is formed so as to be slightly longer than the
holding pins 24, and one insert pin 25 per work 26 is provided in a
position corresponding to the axis of rotation at the center of the
work 26. The present embodiment has twelve (12) sets consisting of
four holding pins 24 and one insert pin 25 for washing twelve (12)
works at a same time.
Next, how to use the washing device of the present embodiment will
be described.
First, as shown in FIG. 5, the work 26 such as a polygonal
reflecting mirror having a hole portion 64 is put on the holding
pins 24 and the insert pin 25. The axis of the hole portion 64 in
the work 26 is approximately matched with the axis of the insert
pin 25 to have a predetermined clearance c between the hole portion
61 and the insert pin 25. In this state, a washing step, a rinsing
step, and a drying step are performed by washing apparatus shown in
FIG. 6.
FIG. 6 is an explanatory drawing schematically showing washing
equipment to be used in the present embodiment. Works 26 (not shown
in FIG. 6) mounted on the pallet 1 shown in FIGS. 2 to 5 are dipped
into a first degreasing bath 52 filled with an organic solvent such
as 1,1,1-trichloroethane, etc. as nonaqueous liquid heated to about
40.degree. C. to 50.degree. C. by a heater (not shown) to finish a
first degreasing step. An organic solvent used in the first
degreasing step has been stored by overflowing (OF) the organic
solvent used in a next step, i.e., a second degreasing step. Next,
the works 26 are moved to the second degreasing step in a second
degreasing bath 53 filled with an organic solvent. An organic
solvent used in the second degreasing step has been stored by dew
formation of vaporized organic solvent (organic solvent vapor) used
in a next step, i.e., a third degreasing step. Next, the works 26
are moved the third degreasing step in the aforementioned vaporized
organic solvent (organic solvent vapor) in a third degreasing bath
54.
The works 26 which have been subjected to the first to third
degreasing steps are dipped into a first ultrasonic washing bath 55
filled with alkalescent surface-active agent as hydrophilic liquid
to finish a first washing step, and also to finish a second washing
step in a similar second ultrasonic washing bath 56.
The works 26 which have been subjected to the first and second
washing steps are moved to a shower bath 57 and are showered
therein with pure water (city water may be used) to finish a first
rinsing step. Next, the works 26 are dipped into a third ultrasonic
washing bath 58 filled with pure water to finish a second rinsing
step. Pure water used in the second rinsing step has been stored by
overflowing (OF) the pure water used in a next step, i.e., a third
rinsing step. Next, the works 26 are dipped into a fourth
ultrasonic washing bath 59 filled with pure water purified to an
ordinary purity (resistivity is about 1 M.OMEGA..cm), called
primary pure water to be described later to finish the third
rinsing step. Furthermore, the works 26 are dipped into a pure
water bath 60 filled with pure water purified to a similar purity
to the third rinsing step to finish a fourth rinsing step.
The works 26 which have been subjected to the first to fourth
rinsing steps are moved to a prestep of a drying step to be
described later. The works 26 are dipped into an ultra-pure water
bath 61 filled with ultra-pure water (resistivity is about 10
M.OMEGA..cm) heated to about 50.degree. C. by a heater (not shown)
to finish the prestep of the drying step. The works 26 are taken
out from the ultra-pure water, and are exposed to hot air heated to
about 60.degree. C. by a heater (not shown) and cleaned by a HEPA
filter 62 to finish the drying step. Then, the works 26 are moved
to a reflecting film coating step for coating mirror surfaces (side
surfaces) thereof with oxide film.
According to the present embodiment, when the aforementioned
washing, rinsing and drying steps are performed and metallic bodies
are conveyed between steps, the works 26 can be moved together with
the washing jig so that the works 26 may not contact each other,
thereby preventing an impact on mirror surfaces of the works 26 and
any other similar problems.
Conventional ultrasonic washing baths which generate ultrasonic
waves of around 28 kHz and are widely used for washing glass and
the like, are not suited for use with the first to fourth
ultrasonic washing baths 55, 56, 58, and 59, because an erosion
will occur on the surface of the work 26 of aluminum or the like.
To suppress such erosion, it is preferable to use an ultrasonic
washing bath generating ultrasonic waves of 100 kHz or more.
However, an ultrasonic washing bath generating ultrasonic waves of
over 800 kHz are not preferable because of difficult procurement
and weaker cavitation. Consequently, it is preferable to use an
ultrasonic washing bath generating ultrasonic waves of around 100
to 800 kHz. Also, the present embodiment uses the ultrasonic
washing bath in both washing and rinsing steps , but it is possible
to use the ultrasonic washing bath in either washing or rinsing
step. Furthermore, it is preferable to move the works 26 up and
down in each of the ultrasonic washing baths 55, 56, 58, and 59,
because the works 26 can be struck uniformly by ultrasonic waves so
that washing effect is improved and surface erosion is prevented
more effectively.
In the aforementioned drying step, the washing liquid does not stay
in the hole portion 64 in the work 26 but drops by own weight
thereof along the insert pin 25. This is called liquid drainage.
Also, since the holding pins 24 keep the bottom portion of the work
26 sufficiently apart from the top surface of the jig base plate
22, the work's bottom portion is also washed sufficiently.
The aforementioned clearance c varies depending on the material of
the work 26, the size and shape of the hole portion 64, the
composition of washing liquid, etc. For example, for the work 26 of
aluminum having a circular hole portion 64 of 4 to 6 mm in
diameter, it is preferable that the clearance c is 1 to 3 mm when
washing liquid is water.
The material of the holding pin 24 and the insert pin 25 is
preferably high in wettability with washing liquid for better
liquid drainage.
As described above, according to the present embodiment, an insert
pin is inserted into a hole portion in a work so that a
predetermined clearance is formed therebetween, thereby providing
good liquid drainage from the work and performing the steps of
washing, rinsing, and drying as one continuous process without the
washing liquid's staying. Consequently, the yield of works
improves, and a quality improvement and a cost reduction are
attained.
Also, when executing the washing, rinsing and drying steps and
carrying metallic bodies between steps, works can be conveyed
together with a washing device so that the works may not contact
each other, thereby preventing an impact on mirror surfaces of the
works and any other similar problems.
* * * * *